What was found in Rapid City's water
The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.
| Contaminant | Level vs EPA limit | Suppliers | Source |
|---|---|---|---|
| Nitrate | 1443.5 µg/L 14% of the EPA limit 10000 µg/L Main supplier: RAPID CITY · 72,009 people · 2019
Highest in the city: 10600 µg/L — SIPHON HILL WATER ASSOCIATION · 68 people · 2019 | 46/67 | SYR4 |
| Fluoride | 1600 µg/L 40% of the EPA limit 4000 µg/L Highest in the city: RIMROCK HIGHLAND ESTATES COMM ASSOC · 66 people · 2017 | 49/67 | SYR4 |
| Copper | 311.7 µg/L 24% of the EPA limit 1300 µg/L Main supplier: RAPID CITY · 72,009 people · 2018
Highest in the city: 794.3 µg/L — STAGEBARN SANITARY DISTRICT · 295 people · 2019 | 64/67 | SYR4 |
| Barium | 134.5 µg/L 6.7% of the EPA limit 2000 µg/L Main supplier: RAPID CITY · 72,009 people · 2019
Highest in the city: 533.7 µg/L — WESTBERRY TRAILS WATER USERS ASSOC · 155 people · 2018 | 51/67 | SYR4 |
| Nitrite | 200 µg/L 20% of the EPA limit 1000 µg/L Main supplier: RAPID CITY · 72,009 people · 2018 | 2/67 | SYR4 |
| TTHM | 28.85 µg/L 36% of the EPA limit 80 µg/L Main supplier: RAPID CITY · 72,009 people · 2019
Highest in the city: 82.3 µg/L — SHERIDAN LAKE HIGHLANDS, INC. · 85 people · 2019 | 38/67 | SYR4 |
| Total Haloacetic Acids (HAA5) | 18.45 µg/L 31% of the EPA limit 60 µg/L Main supplier: RAPID CITY · 72,009 people · 2019
Highest in the city: 67.06 µg/L — SHERIDAN LAKE HIGHLANDS, INC. · 85 people · 2019 | 14/67 | SYR4 |
| Lithium | 23.4 µg/L No EPA limit set Highest in the city: RAPID VALLEY SANITARY DISTRICT · 11,408 people · 2024 | 1/67 | UCMR-5 |
| Gross Alpha, Excl. Radon And U | 6.594 pCi/L 44% of the EPA limit 15 pCi/L Main supplier: RAPID CITY · 72,009 people · 2018
Highest in the city: 17.305 pCi/L — PRAIRIE HAVEN SUBDIVISION · 105 people · 2019 | 45/67 | SYR4 |
| Selenium | 17 µg/L 34% of the EPA limit 50 µg/L Highest in the city: RIMROCK HIGHLAND ESTATES COMM ASSOC · 66 people · 2017 | 5/67 | SYR4 |
| Lead | 4 µg/L 27% of the EPA limit 15 µg/L Main supplier: RAPID CITY · 72,009 people · 2018
Highest in the city: 11.3 µg/L — RAPID CITY MOBILE HOME PARK · 170 people · 2018 | 64/67 | SYR4 |
| Combined Uranium | 11 µg/L 37% of the EPA limit 30 µg/L Highest in the city: TIMBERWOOD PARK ESTATES · 283 people · 2019 | 3/67 | SYR4 |
| Arsenic | 6 µg/L 60% of the EPA limit 10 µg/L Main supplier: RAPID CITY · 72,009 people · 2019 | 9/67 | SYR4 |
| Gross Beta Particle Activity | 3.5 pCi/L No EPA limit set Main supplier: RAPID CITY · 72,009 people · 2018 | 1/67 | SYR4 |
| Chromium | 2.2 µg/L 2.2% of the EPA limit 100 µg/L Highest in the city: PONDEROSA PARK · 50 people · 2012 | 4/67 | SYR4 |
| Mercury | 0.2000 µg/L 10% of the EPA limit 2 µg/L Highest in the city: CARRIAGE HILLS · 267 people · 2012 | 1/67 | SYR4 |
| Lead | 0.0060 mg/L 40% of the EPA limit 0.0150 mg/L Main supplier: RAPID CITY · 72,009 people · 2024
Highest in the city: 0.0140 mg/L — EDELWEISS MOUNTAIN IMPROVEMENT ASSOC · 70 people · 2024 | 66/67 | LCR |
| PFHXS | 0.0056 µg/L No EPA limit set Main supplier: RAPID CITY · 72,009 people · 2025
Highest in the city: 0.0058 µg/L — RAPID VALLEY SANITARY DISTRICT · 11,408 people · 2024 | 2/67 | UCMR-5 |
| PFOS | 0.0057 µg/L No EPA limit set Highest in the city: RAPID VALLEY SANITARY DISTRICT · 11,408 people · 2024 | 1/67 | UCMR-5 |
Water suppliers serving Rapid City
The 50 largest of 67 suppliers serving Rapid City, by population served.
Frequently asked questions about Rapid City tap water
Is Rapid City tap water safe to drink?
EPA testing detected 19 contaminants in the water serving Rapid City. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.
How many water suppliers serve Rapid City?
67 public water suppliers report drinking-water monitoring for Rapid City, South Dakota to the EPA. Each is listed above with its population served.
What contaminants are in Rapid City's water?
The contaminants EPA monitoring detected in Rapid City include Nitrate, Fluoride, Copper, Barium, Nitrite. The full list, with the level at the main supplier and the data source, is in the table above.
Where does this data come from?
Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.